大约有 41,000 项符合查询结果（耗时：0.0352秒） [XML]
GROUP BY to combine/concat a column [duplicate]
...
SELECT
[User], Activity,
STUFF(
(SELECT DISTINCT ',' + PageURL
FROM TableName
WHERE [User] = a.[User] AND Activity = a.Activity
FOR XML PATH (''))
, 1, 1, '') AS URL...
Why is unsigned integer overflow defined behavior but signed integer overflow isn't?
....6.1:3:
Values stored in unsigned bit-fields and objects of type unsigned char shall be represented using a pure binary notation.
C99 6.2.6.2:2:
If the sign bit is one, the value shall be modified in one of the following ways:
— the corresponding value with sign bit 0 is negated (sign and magni...
Remove duplicates in the list using linq
...
var distinctItems = items.GroupBy(x => x.Id).Select(y => y.First());
share
|
improve this answer
|
follow
|
...
Where are my postgres *.conf files?
...alives_idle = 0 # TCP_KEEPIDLE, in seconds;
# 0 selects the system default
#tcp_keepalives_interval = 0 # TCP_KEEPINTVL, in seconds;
# 0 selects the system default
#tcp_keepalives_count = 0 # TCP_KEEPCNT;
# 0 selects the...
How can I easily convert DataReader to List? [duplicate]
... writing an extension method for this:
public static IEnumerable<T> Select<T>(this IDataReader reader,
Func<IDataReader, T> projection)
{
while (reader.Read())
{
yield return projection(reader);
}
}
You can then use LINQ...
Create batches in linq
... int maxItems)
{
return items.Select((item, inx) => new { item, inx })
.GroupBy(x => x.inx / maxItems)
.Select(g => g.Select(x => x.item));
}
}
and the usage would be:
List<int> list = new L...
querySelector search immediate children
...
Though it's not a full answer, you should keep an eye on the W3C Selector API v.2 which is already available in most browser, both desktop and mobile, except IE (Edge seems to support): see full support list.
function(elem) {
return elem.querySelectorAll(':scope > someselector');
};
...
How to sort the result from string_agg()
...
With postgres 9.0+ you can write:
select string_agg(product,' | ' order by product) from "tblproducts"
Details here.
share
|
improve this answer
|...
What is the type of lambda when deduced with “auto” in C++11?
...ually make use of __PRETTY_FUNCTION__, as in template<class T> const char* pretty(T && t) { return __PRETTY_FUNCTION__; }, and strip off the extra if it starts to get crowded. I prefer to see the steps shown in template substitution. If you're missing __PRETTY_FUNCTION__, there are alt...
Escaping keyword-like column names in Postgres
...). A delimited identifier is always an
identifier, never a key word. So "select" could be used to refer to a
column or table named "select", whereas an unquoted select would be
taken as a key word and would therefore provoke a parse error when
used where a table or column name is expected.
...